Sleeping Beauty (SB) is a transposon system that has been extensively shown to be capable of mediating integration of new gene sequences into the chromosomes of target cells and tissues. At Discovery Genomics, Inc. (DGI), we are working to develop the SB transposon system for human gene therapy, with hemophilia as our lead project. During initial Phase II SBIR studies, we demonstrated effective delivery of SB transposon DNA to the liver of dogs. Single or double balloon catheters were used to achieve whole or partial occlusion of the liver followed by rapid, high volume retrograde infusion of DNA containing solution into the hepatic venous circulation. Results from these experiments (reporter gene expression was observed for six weeks following infusion) place DGI at the forefront of non-viral gene therapy efforts targeting the liver in large animals. Based on these results and recent feedback from the Food and Drug Administration, in this Phase II competing renewal application we propose further preclinical studies to address issues of safety, scale-up to the size of humans, and efficacy in a large animal model of hemophilia. The Specific Aims are; (i) To develop double balloon catheters capable of delivering SB transposon DNA to the liver in humans and to test the safety and effectiveness of these catheters for DNA delivery in pigs as a large animal model of comparable size to human beings; (ii) To extend the duration of transgene expression after delivery of SB transposons to the liver of normal dogs, using DGI's unique canine secreted alkaline phosphatase (cSEAP) reporter system; (iii) To deliver SB transposons encoding canine clotting factor IX (cFIX) to the liver of cFIX deficient dogs, testing for long-term expression of cFIX and improved clotting function as a large animal model for SB mediated gene therapy of hemophilia B. Results from these studies will provide necessary preclinical data for subsequent submission of an Investigational New Drug application with the FDA for treatment of hemophilia B using the SB transposon system, with subsequent growth and commercial development of Discovery Genomics, Inc.